Sounds like a good middleground to start: add ``PySendResult `` and `PySendResult PyGen_Send(PyGenObject*, PyObject* PyObject**)` specific to generators and coroutines. Subsequent changes could introduce `PySendResult PyIter_Send(PyObject*, PyObject*, PyObject**)` that would be more generic (call tp_next, invoke "send" or maybe in the future use dedicated slot for "send" operator so i.e. asyncio.Future or Cython coroutines could benefit from the same optimization)